The present invention relates to an outer peripheral structure for a liquid crystal display device, and more particularly to a system for attaching a polarizing plate to a liquid crystal cell.
In order to clarify the background of the present invention, an example of a conventional liquid crystal display device will now be briefly explained with reference to FIG. 1. A pixel array in the form of a matrix is formed on one inner surface of a substrate 101. Each pixel is composed of a thin film transistor (TFT) for driving and a pixel electrode 102 formed by patterning a transparent conductive film. A drain electrode of each TFT is connected to the associated pixel electrode 102, a source electrode thereof is connected to a data line 104, and a gate electrode thereof is connected to a scan line 105. The substrate in which the TFTs and the like are thus formed in an integral manner will be referred to as a TFT substrate. Color filters (CF) 107 composed of RGB three-primary color segments and opposite electrodes 108 are laminated on one inner surface of the other substrate 106. The individual color filter segments are in alignment with the pixel. The substrate in which the color filters and the like are thus formed will be referred to as a CF substrate. A liquid crystal layer 109 is filled in a gap defined between the TFT substrate and the CF substrate 106. Polarizing plates 110 and 111 are attached directly to the outer surfaces of both the substrates 101 and 106, respectively. When the TFTs are electrically connected through the scan line 105 for every row, an image signal to be fed from the data line 104 is written in each pixel electrode 102. A voltage is applied between the pixel electrode 102 and the opposite electrode 108 in response to the stored image signal to thereby change a molecular arrangement of the liquid crystal layer 109. This change is picked up as a change in transmittivity to thereby bring about the image display. The liquid crystal display device having such a structure is referred to as an active matrix type LCD. It should be noted that a liquid crystal display device to which the present invention pertains is not limited to this type LCD and it should be understood that the LCD is shown by way of example.
A task to be solved by the present invention will now be briefly explained with reference to FIG. 2. A liquid crystal cell 201 has a structure in which a TFT substrate 202 and a CF substrate 203 are bonded together by a sealant 204 and a liquid crystal layer 205 is held in a gap between both the substrates. Respective polarizing plates 206 and 207 are attached directly to outer surfaces of the two substrates. The unit has a disadvantage such that, when a foreign matter such as dust or fluff is attached to the polarizing plates during bonding, a quality of the article would be deteriorated. In particular, it is impossible to remove the foreign matter entrained in the bonded interfaces between the polarizing plates and the substrates without as the polarizing plates being replaced by new ones. The deterioration in display quality due to the foreign matter would be remarkable in particular when the liquid crystal display device is applied to a viewfinder or a projector. In such an application, the illumination is achieved by a light source 208 located behind the liquid crystal cell 201 and at the same time, an image surface illuminated through an enlargement lens system 209 is enlarged and projected forwardly. In general, the focal plane of the enlargement lens system 209 is in alignment with the layer of the color filter formed in the CF substrate 203. However, in many cases, a thickness of each substrate is about 1 mm and is within a depth of focus of the enlargement lens system 209. As a result, the foreign matter attached to the interface between the substrate and the polarizing plate is also projected with a relatively clear outline or contour, thereby considerably degrading the image quality.